Load-supporting metallic floor panels



Feb. 22, 1966 D. c. GRAHAM ETAL LOAD-SUPPORTING METALLIC FLOOR PANELS 2 Sheets-Sheet 1 Filed July .16, 1963 12 I8 IO I INVENTORS DOA 44o CI GJQMAM 0044' 6'. My BY Games! 6- 53:91PM

' x7 aewzr Feb. 22, 1966 D. c. GRAHAM ETAL 3,236,018

LOAD-SUPPORTING METALLIC FLOOR PANELS /3 INVENTORS Don/n40 C. Glen/07M 0n: E. f/f/N GEORGE H- Snenu United States Patent 3,236,018 LOAD-SUPPORTING METALLIC FLOOR PANELS Donald C. Graham and Dale E. Hein, York, and George H. Sta-am, Hellam, Pa., assignors to Tate Engineering, Inc., Baltimore, Md.

Filed July 16, 1963, Ser. No. 295,364 8 Claims. (Cl. 52619) This invention pertains to a structural panel and, more particularly, to a structural panel preferably formed from sheet metal and suitable for use in numerous capacities, especially to serve as load-supporting means, of which floor and deck constructions of various kinds comprise several examples, but without restriction thereto.

The construction of load-supporting panels intended to serve in such capacities as floors of both building structures as well as vehicles and other types of movable equipment such as airplanes and marine uses, usually present serious problems in regard to strength in comparison with the weight and depth. I-f unlimited weight or depth may be utilized in designing floor structures and the like, the solution of the strength problem is relatively easy. However, particularly in free access or elevated types of floors, as well as other types, for certain building structures, and also in regard to floors for various kinds of motor vehicles including trucks and passenger automobiles, buses, railway rolling stock of various kinds, and in addition, aircraft of all kinds and many types of decks and flooring uses in marine equipment, excessive weight either can not be tolerated or may be tolerated to only limited degrees. Nevertheless, floors, decks and the like in such structures and items must be designed to support certain minimum unit weight loads while not exceeding certain total weight units of the floor and deck structures per se.

Certain floor and deck structures used at present have attempted to solve the aforementioned problems in various ways such as by the use of extruded or cast sections formed from metal and providing reinforcing beam-like members positioned at spaced intervals across and integral with a load-sustaining sheet but construction of this type is relatively expensive and also is quite heavy in comparison with the capabilities of sustaining loads without undue deflection. Further, especially cast or extruded sections offer rigidity in only one direction. Other attempts to produce suitable panels have included the use of plywood of suitable thickness, usually bound around the edges with wear-enduring strips of various kinds including metal strips fastened thereto by suitable means but, for purposes of providing adequate loadsustaining properties without undue deflection, thicknesses for panels of this type have been such that the weight of the panels per se is substantial.

It is the principal object of the present invention to provide a structural panel which preferably has a minimum thickness relative to load-sustaining area and, more importantly, has a very substantial capability of supporting very substantial limits of concentrated loads in comparison with the weight of such panels per se, one of the principal attributes of such panels also being that it is relatively inexpensive to construct, in comparison with panels presently used in similar capacities.

Another object of the present invention is to form such aforementioned structural panels of sheet metal of suitable gauge, only two sheets of such metal being required for purposes of providing uninterrupted upper load-sustaining service and comprising a compression member, the second sheet being spaced from the first sheet in a direction perpendicular thereto and comprising a tension-sustaining member, whereby in cross-section, such panel resembles a form of truss construction including portions of one of said sheets which are struck therefrom and are bent to extend into engagement with the other sheet and maintain the two spaced apart a predetermined distance as well as transmitting load stresses from the compression member to the tension-sustaining member. 1

A further object of the present invention is to form such structural panels from two sheets of metal of similar area and shape, but not necessarily of the same gauge, and slit or pierce one of said sheets to enable portions or sections thereof to be bent from the plane of the sheet to form strut members engageable with the other, uninterrupted sheet to which the aforementioned sheet is connected.

Still another object of the invention is to construe the aforementioned structural panel from said pair of sheets of metal and connect the coengaging portions thereof preferably by simple and inexpensive means such as spot or other types of welding, appropriate adhesives or bonding agents, rivets or bolts, the configurations of the sheets when in condition to be connected being such as readily to permit the use of spot welding equipment or other tools required for purposes of connecting said sheets together and particularly for connecting the strut means between the two sheets in operative position so as to secure the two sheets permanently together.

A still further object of the invention is to construct preferably the lowermost sheet from which the struts are formed so as to provide a series of preferably parallel strips of metal which extend between opposite edges of the sheet and thereby comprise tension-sustaining zones or areas in said sheet.

Ancillary to the foregoing object, a further objective is to provide a grid arrangement of transversely disposed sets of preferably parallel strips of metal in said lowermost sheet, while the portions of said sheet which are struck therefrom incident to forming said strips or ribbons of metal are bent appropriately to comprise the strut members which maintain the upper, compression or loadsustaining sheet in desired spaced relationship relative to the lower or tension-sustaining sheet.

Still another embodiment of the invention is to provide a plurality of different patterns or arrangements of fingers or tongues which are struck from the second or lower sheet of metal, all preferably in a uniform pattern, and providing preferably closely and evenly spaced struts disposed in overall patterns throughout the areas of said sheets so as to minimize the possibility of bending or deflecting of the rigid, load-sustaining compression sheet which is uppermost in the panel when the panel is arranged in operative position.

A still further object of the invention is to provide preferably continuous edge flanges, on both of said sheets, said flanges being inter-related and connected together in such manner as to afford ample stiffening of the edges of the panel as well as provide finished surfaces for said edges.

Details of the foregoing objects and of the invention, as well as other objects thereof, are set forth in the following specification and illustrated in the accompanying drawings comprising a part there.

In the drawings:

FIG. 1 is an exemplary perspective view of a structural panel embodying the principles of the present invention and being of the type which is provided with a finished, wfear-resisting surface sheet arrangement on the top there- 0 FIG. 2 is an exemplary vertical sectional view of the panel shown in FIG. 1, but on a larger scale, and showing details of one embodiment of the two sheets from which the panel is formed.

formed from two sheets of metal. "square or rectangular, depending upon the pattern of FIG. 3 is a perspective bottom view of the panel illustrated in FIG. 1, but shown on a somewhat larger scale than employed in FIG. 1, and illustrating the tension-sustaining strips of the lower sheet as well as the strut means extending between the pair of sheets com prising the panel.

FIG. 3a is a fragmentary bottom plan view of a single opening of the panel.

FIG. 4 is a plan view of the lower sheet of the panel shown in FIGS. 1 and 2 and illustrating one embodiment of piercing pattern which may be employed to form integral strut members which are to be bent from the plane of said sheet.

FIG. 5 is a fragmentary vertical sectional view, on a larger scale than in the preceding figures, and illustrating an exemplary construction of peripheral flanges on the sheets comprising the panel, this illustration showing one embodiment of panel around which a finished channel strip may be mounted and upon which a finished floor or deck surface sheet may be positioned to sustain wear.

FIG. 5a is a fragementary vertical sectional view of a different embodiment of the invention from that shown in FIG. 5.

FIG. 5b is a fragmentary vertical sectional view of a still different embodiment of the invention from those shown in FIGS. 5 and 5a.

FIG. 6 is a fragmentary vertical sectional view on a similar scale to that used in FIG. 5 and showing an exemplary means for connecting the outer end of strut members from the lowermost sheet to the inner surface of the uppermost sheet of the panel made in accordance with the present invention.

FIG. 7 is a fragmentary perspective view of one corner of the panel shown in FIG. 1 but illustrated on a larger scale than in FIG. 1 and illustrating details of the corner construction of such panel.

FIGS. 8, 10 and 12 respectively are exemplary fragmentary plan views each comprising a portion of a lower sheet and having a different embodiment of piercing or slitting pattern for the lower sheet of the panel for purposes of forming integral strut means therefrom and FIGS. 9, 11 and 13 show fragmentary bottom plan views of the same portions of said sheets having the corresponding strut-forming patterns shown in FIGS. 8, 10

and 12 but after the slitted metal sheets have been processed to strike the strut-forming tongues therefrom and bend the same into'operative position for engagement against the inner surface of the uppermost load-sustaining sheets of the various panels.

FIG. 14 is an exemplary vertical sectional view of an airplane fuselage in which a floor is illustrated utilizing structural panels formed in accordance with the present invention.

In accordance with the preferred construction of the structural panel comprising the present invention, it is These sheets may be panel desired. They, may even be in the shape of elongated, obling panels resembling planking. In the event a different shape of the panelin plan view is desired, it is conceivable that such shape, in planview may comprise other geometric figures than either a square or an average or oblong shaped rectangle but, for most practical purposes, it is assumed that either a square or generally rectangular shape of the panel in plan view will conform the same to most of the anticipated and desired uses of such panels.

While for most uses, it is conceivable that the preferred material from which the panels are formed shall be sheet steel, it is realized that especially for aircraft use, where excess weight is always a problem, the use of sheet aluminum or other relatively light-weight alloys is preferable to steel. The same may also be true with respect to certain vehicular use to which structural panels comprising the present invention may be applied. Still other appropriate materials may be used, especially where certain uses or atmospheres dictate.

In accordance with the invention, the preferred basic structure of such panels, in longitudinal cross-section, resemble a truss construction in that, as will be seen particularly from FIG. 2, there is an upper, load-sustaining sheet), which preferably is planar and uninterrupted throughout its area, said sheet comprising a compression resisting or sustaining sheet or member. Vertically spaced from said sheet 10 is a lower or tension-sustaining sheet 12 which is provided with struts 14 extending therefrom into engagement with the inner surface of upper sheet 10.

It is to be understood that the exemplary vertical. sectional illustration of structural panel illustrated im FIG. 2 is only of a single embodiment of the present. invention, it being understood that other specifically illus-- trated embodimen ts are shown in other figures and illus-- trated hereinafter in the specification. However, the embodiment shown in FIG. 2 will serve to illustrate the: basic principle of the truss-type cross-sectional structure:

' of the panel and by which an effective bracing is provided This is possible due to the ability of the upper sheet of the panel to resist or sustain compression forces, while the lower sheet is capable of resisting or sustaining tension forces, the struts between being employed to transmit the load forces from the upper sheet to the lowerv sheet.

One of the important advances made by the present invention in the construction of structural panels comprises the very simple and inexpensive manner in which the aforementioned truss construction is formed, simply through the employment of two sheets of metal. More importantly, one of said sheets of metal, at least throughout its area defined by the peripheral edges preferably is planar and uninterrupted so as to comprise either a loadsustaining surface per se or a surface upon which a finished sheet of material of suitable type, such as lino- I leum, floor tile, terrazzo, or the like, may be disposed for direct support of load means thereon. Accordingly, only the lower, tension sheet is interrupted for purposes of performing a dual function, namely sustaining tension stresses and also, without the use of any additional material, providing completely adequate strut means which extend upward therefrom to engage the upper sheet which sustains the compression stresses from loads imposed thereon.

' illustrated in plan View, it will be seen that said sheet across the entire length or width of the sheet. 70.

initially is slit or pierced by a plurality of H- or I-shaped incisions 16. Preferably, it will be seen that these incisions are made in even rows extending between opposite: edges of the sheet and parallel to each other, the adjacent incisions of similar patterns being former preferably at stamping machinery through the use of appropriate dies.

It will be seen also from FIG. 4 that sheet 12 also is provided with a series of elongated zones or strips 18, the same comprising sets of parallel rows thereof, one set being vertical with the drawing sheet upon which FIG. 4 appears, while the other is transverse thereto, whereby the intersecting zones of strips 18 of metal define a grid and the strips 18 comprise elongated tension-sustaining portions or members capable of supporting the upper sheet against appreciable deflection when loads even of a concentrated, relatively heavy type are exerted against sheet 10 from the top thereof, as envisioned from FIG. 2 for example.

The H- or I-shaped incisions 16 each form a pair of abutting tongues which, when bent from the plane of sheet 12, form the struts 14 but said tongues are longer than the struts 14 actually needed to be simply to extend into engagement with the undersurface of upper sheet 10. Accordingly, the outer ends 20 of struts 14 are bent into parallelism with the undersurface of upper sheet 10, as best shown in detail in FIG. 6, and said extensions 20 are fixedly connected to the undersurface of sheet 10 by any suitable means such as bolts, riveting, bonding or the equivalent, but preferably by welding, especially spot or line welding. As will be clearly seen especially from FIG. 6, the outer ends 20 of the struts 14 are substantially at least half as long as said struts and as wide as said struts, whereby said bent ends afford very substantial areas of reinforcement of said upper sheet 10 against bending at localized areas such as when subjected to concentrated load forces. Also, the struts 14, being preferably substantially at a right angle to bent ends 20 strengthen the same against deflection and, conversely, the bent ends 20 also brace the struts 14 against buckling within the planes thereof.

By reference to FIG. 3 and particularly FIG. 3a, which latter shows a fragmentary bottom plan view of a single opening 22 outlined by the intersecting parallel sets of strips 18, it will be seen that the outer ends 20 of struts 14 are disposed within spaces outlined by the openings 22, whereby such tools as may be required to connect the same or welding contacts or electrodes very conveniently can be applied against the outer surfaces of the ends 20 of the struts 14 when in abutment with the inner surface of sheet 10, the other welding electrode, when spot welding is used, being applied against the outer surface of sheet 10, whereby such welding permanently connects the sheets together and may effected quickly and without difliculty, at a minimum of cost, especially since no special jigs or equipment of any consequence, or at least only minimum types of the same, normally will be required to effect such welding. However, even if special tooling jigs, or the like, are required, the advantages afforded by the invention will more than offset the cost of such tooling and jigs.

The sheet 12, following the placement of the incisions 16 therein, readily is formed into the configuration shown in side elevation, for example, in FIG. 2, but foreshortened in length for compactness in said view, by suitable dies, such as of the progressive type. Not only are the dies used to bend the tongues formed by the incisions 16 into the embodiment of struts 14 shown in FIGS. 2 through 4 but elongated marginal areas extending along each side of the sheet 12 likewise are bent, preferably at a right angle to the plane of sheet 12 in order to form marginal bracing flanges 24 which extend along all four edges of the sheet 12 to impart rigidity to the edges of the panels.

Flanges 24 not only impart rigidity and strength tothe sheet to resist bending but also provide additional effective means by which sheet 12 is connected to sheet 10. A similar die to that which forms the marginal flanges 24 on sheet 12 also may be employed to form similar marginal flanges 26, see FIG. 5, on upper sheet 10, said flanges preferably also extending entirely along each edge of sheet 10. As also seen from FIG. 5, the flanges 26 on sheet 10 preferably are slightly shorter than the distance between the two sheets, but the exterior surfaces of flanges 26 preferably closely engage the interior surfaces of flanges 24 on sheet 12, as seen from FIG. 5, and said closely abutting flanges are connected permanently and inexpensively by any suitable means, of which line welding or spot welding, at preferably evenly spaced locations, for example, longitudinally along said flanges is highly suitable, although bolts, rivets, adhesive bonding or the like may be used if desired.

The reticulated nature of plate 12, after the struts 14 have been bent angularly to the surface thereof, permit ample and easy access to the inner surfaces of the flanges 26 on sheet 10 for the placement of welding contacts or electrodes against said flanges while the opposite contacts or electrodes, when spot or line welding is used, are placed against the exterior of flanges 24 of sheet 12. Following such connection of the marginal flanges 24 and 26 of the spaced parallel metallic sheets comprising the panel, as well as fixedly connecting the ends 20 of the struts 14 against the inner surface of sheet 10, the formation of the basic construction of the structural panel comprising the present invention is completed except for necessary or desired finishing operations such as painting and/or the application of any of a variety of finished surface sheets or blocks 28, such as linoleum, suitable plastic sheeting, wood sheets or blocks, or the like, against the upper surface of metallic sheet 10, bonding being effected by a suitable cement or the like. Such added sheets, blocks, or the like may be applied on the job site, if desired.

To enhance the utility of the structural panel further, the uppermost edges 30 of the flanges 24, as seen in FIG, 5, preferably are spaced outwardly relative to flanges 26, thereby increasing the rigidity of the sides of said panels, but also in order to accommodate thereon a channel-shaped finish strip 32, which also may be formed from material similar to the finish surface sheet 28, and additionally including even more yieldable material such as suitably prepared rubber, especially if sealing is desired between the edges of adjacent pairs of such panels, particularly where the panels serve as floor surfaces, decking, or the like and it is desired that no space of appreciable consequence be formed between such adjacent panels. Such connection may be substantially gas tight to permit such panels to define a plenum chamber, for example. As a result of spacing the upper edges of the flanges 24 from the flanges 26, the flanges 24 necessarily are formed exteriorly of flanges 26.

Where no additional finished surface sheet, tile, block, or the like is desired on the upper surface of the panels, the marginal flanges may be formed as shown in FIG. 5a, wherein the sheets 10 and 12 will be the same as in the panel shown in FIG. 5, as are the flanges 26 on the upper sheet 10. However, sheet 12 has substantially flat marginal flanges 24 which preferably terminate either flush with the upper surface of sheet 10 or slightly below it to provide a suitable finished edge, especially where aesthetics are required.

By reference to FIG. 512, still another possibility of finished surface for the panels are illustrated, especially where the panels are to be used as flooring, decking, or the like. The sheets 10 and 12 preferably are the same as in the constructions shown in FIGS. 5 and 5a, likewise with the flanges 24 and 26, including the uppermost edges 30 of flanges 24. However, a metallic channel or heading 32, preferably formed from metal, such as aluminum or brass, is applied to the edges 30 to serve as a border to receive marble terrazzo, suitable cement composition, or the like and appropriately finished, by grinding or the like, either at the factory or at the job site. Thus, a very wide range of possible finishes is afforded by the various embodiments of the invention.

Structural panels which include the basic principles of construction and particularly the tension-sustaining kinds of supporting stringers, girders, or beams. panels may be attached thereto conveniently, for example, 'by tack welding, or other means, applied in the field, or

strips 18 in lower sheet 12, rigid load-receiving and compression-sustaining plate 10, transverse struts 14 extending between said plates, and the edge connecting means for the plates comprising specifically by way of example,

but without restriction thereto, the connected overlapping edge flanges 24 and 26, comprise a rigid and very strong panel construction which is suitable for a wide range of uses, principally in floor, deck or roof capacities for various types of buildings of all kinds, and also vehicles, conveyances and the like. For example, as shown in FIG. 14, anexemplary outline or diagrammatic showing of an exemplary vertical sectional view of an airplane fuselage is illustrated, the same comprising a plurality of structural floor panels 34, which may be suitably supported upon appropriate posts or columns 36 extending to the frame ofthe fuselage for example. Such fioor panels 34 may embody the basic construction of the. structural panels described above and illustrated in FIGS. 1 through 6, if desired, but under such circumstances, the sheets 10 and 12 from which the panels are formed in this regard preferably are made from suitable sheet aluminum or aluminum alloy stock so as to afford 'minimum weight for maximum rigidity and strength to resist deflection when loads are placed thereon.

In addition to panels embodying the present invention being used for floors of aircraft however, such panels 'readily can be used as partitions or bulk heads, as well as doors, in aircraft and other types of vehicles. Railway rolling stock of various kinds and especially passenger coaches are highly appropriate for use of such panels as floors, hatch covers for refrigerator cars, and the like. Various kinds of vehicles, especially passenger vehicles such as automobiles, station'wagons, buses and the like comprise appropriate uses for such panels as floors or deck surfaces. These panels also, particularly when constructed of suitable gauge of steel, are appropriate for use as floors in automobile trucks and even railway freight cars, particularly in view of the high ratio of strength relative to weight of the panels per se.

Additional appropriate fields for use of such panels are found in boats and barges of various kinds such as by being employed in the decking, hatch covers, and bulk heads thereof as well as conceivably for use as gang planks and other temporary bridging means of a portable nature, for example. Floors for decompression chambers are another possible use for such panels. Dock boards for use between automobile trucks and a loading dock likewise constitute an appropriate field of use when the gauge of metal and type thereof such as steel are selected appropriately.

Numerous types of building structures offer appropriate uses for such panels as flooring, decking and roofing. Especially in processing plants and laboratories requiring removable floor sections or trap doors to gain access to lines and conduits of various kinds normally below the floor surface, the panels of the present invention find wide use. Flooring of the free access type, especially for supporting electronic equipment requiring extensive numbers and volumes of electrical conduits below the floor surface aiford a particularly appropriate field of use for such panels.

The panels also are highly suitable as flooring or decking for many types of buildings, applied over various The simply supported thereon by gravity. The panels may equally well be used as roofing, especially if it is necessary for the roof to sustain any substantial loads. Appropriate finishes can be used to render such roof waterproof.

In addition to the building trades however, furniture also oifers still another possible use for such panels in providing tops of certain kinds as, for example, in desks .and tables, counters, elevated platforms of various kinds 8. including choral risers and the like comprise-appropriate practical fields of use therefor. Suitable oblong panels may also be used as shelving or planking especially to hold substantial loads as in stock rooms, libraries and the like.

In the preferred construction of thepanels comprising the present invention, and particularly as is shown in the larger scale employed in FIG. 5, it will be seen that the gauge of metal from which sheet 10 is selected is substantially thicker than the gauge of sheet 12. This is due primarily to the fact that sheet 10, being substantially the same overall area as sheet 12, is subjected to compression forces and must withstand against appreciable buckling or bending imposed thereon Within reasonable limits, whereas sheet 12 is subjected only to tension stresses or forces and, particularly where the types and kinds of metal selected for the respective sheets are .the same,- it is possibleto effect this economy in the manufacture of the panel without sacrificing rigidity and resistance to deflection. However, the-invention is not to be restricted to differences in gauge between the upper and lower sheets because certain applications will not demand it, especially where concentrated loads of substantial amounts are not to be'supported on the upper sheet was not to risk localized deflection.

While the-arrangement of incision 16: and the shape of the struts 14 shown in the embodiment in FIGS. 1 through 6 is'highlypractical and satisfactory as an appropriate construction for forming structural panels in accordance with'the principles of the present invention, other configuration of incisions and shapes of struts are possible. It will be noted that th'isembodiment of strut arrangement provides a pair of struts 14' of substantial transverse length respectively adjacent each of two opposite edges of the openings 22' in sheet 12. The outer ends'20 are as long as the struts 14 and are of appreciable area so as to permit the use of a number of applications of spot welding, or other fastening means, on each outer end or flange 20 which is connected to sheet 10.

An additional arrangement of a pair of struts with respect to each' hole, however, is shown in FIG.8 wherein a Z-shaped incision 38 is formed in a fragmentarily illustrated portion of a bottom sheet 12a for purposes of forming a pair of tongues. These tongues are V- shaped and when said tongues are bent along thedotted lines 40, struts 42 are formed which will have end extensions 44 which will function? similarly to the outer ends 20 of struts 14 in .the embodiment shown in FIGS. 1 through 6. The end extensions 44, as seen from FIG. 9, which is a fragmentary bottom plan view of a panel embodying this embodiment of the invention, are shown flatly against the inner surface of supper sheet 10a of said panel, the same being connected thereto by appropriately indicated spot welding connections.

In the event additional struts for each of such openings in the lower sheet are desired for supporting the upper sheets by a more thoroughly or densely arranged pattern of struts on the lower sheet and thereby engaging the inner surface ofv the upper sheet at a greater number of locations than in the embodiments illustrated in FIGS. 1 through 9, it will be seen by reference to the subsequent figures that several additional embodiments are illustrated in which more than two struts, namely, four struts are provided withrespect to each opening formed in the lower sheet. 'In this regard, in FIG. 10, it will be seen that a fragmentary portion of a bottom sheet 12a is shown having an exemplary X-shaped incision 46 made therein which will result in the formation of four V-shaped tongues which, when respective ly bent along the dotted lines 48 will provide four struts 50 which, by reference to FIG. 11, will be seen surrounding a preferably square opening 52 in sheet 12b.

The length of the sides of the opening 52 is selected so-that when the struts 50 are formed as a result of the 9 X-shaped incision 46, each strut will be longer than the space between the upper and lower sheets 10b and 12b of the panel, whereby the outer ends 54 of the struts are bent along the dotted lines shown in FIG. 10 to form the terminal ends 54 which are parallel to and adjacent the inner surface of the upper sheet 10b, said ends being suitably fixed thereto such as by the illustrated spot welding pattern shown in FIG. 11.

Still another embodiment of four struts to an opening type of construction is shown in FIGS. 12 and 13, wherein the bottom sheet 12c is provided with a more complex incision which is in the form of a swastika 56 so as to provide as series of four struts 58, each having an end portion 60, whereby when the struts 58 are bent with respect to lower sheet 120 along the dotted lines 62, the struts 58 will extend into engagement with the inner surface of upper plate 10c, to which the end portions 60 of the struts are connected suitably such as by spot welding as clearly indicated in FIG. 13. It thus will be seen that the square opening 64 is provided with four evenly spaced struts 60 around the perimeter thereof but the end portions of the struts 60 which engage the inner surface of upper plate 100 are longer than the outer ends 54 of the embodiment shown in FIGS. 10 and 11 which engage the inner surface of upper plate 10b.

In regard to the additional embodiments shown in FIGS. 8 through 13, it is to be understood that only a single opening is shown in the exemplary portions of the bottom sheets illustrated in these additional figures, said single opening of each only being exemplary and illustrative of a plurality of such openings and the corresponding complement of struts, similar to the substantial pluralities of openings shown, for example, in the sheet 12 in the embodiment shown in FIGS. 1 through 6 and especially as illustrated in FIG. 3.

From the foregoing, it will be seen that various embodiments of structural panel constructions are shown herein but all employ the same basic principles commonly so as to embody in such panels maximum rigidity for purposes of withstanding appreciable deflection when even substantial concentrated loads are imposed upon the upper sheet of each panel, coupled with a minimum weight of the panels per se. Whereas in various kinds of t-russ constructions, for example, it is common practice to have an upper so-called compression member, a lower so-called tension member, and spacing strut means in between, whereby three types of elements are required to form each truss member, the present invention accomplishes a similar result in a panel construction through the employment of only two sheets of metal in that the lower sheet is so arranged as to not only constitute tension-sustaining means but also provide strut means by which the tension-sustaining lower member is maintained in space relationship to the upper compression-sustaining member.

Due to the firm connection of the side flanges of the upper and lower sheets at the edges of the panels, in crosssection, the edges of the panels are channel-shaped, as is clearly evident from FIGS. 2, 5, a and 5b. This arrangement serves advantageously to brace the edges of the panels against deflection resulting from tension being susstained by the lower sheet of the panels, so as to maintain the side edges of the panels straight.

Further, the strut means are formed through no additional use of material and without wasting any material so as to require the handling of scrap. More importantly however, such struts are provided with adequate strength through no decrease or other diminution in the thickness of the material and through expeditious use of strut extensions in a manner to provide the upper sheet with added bracing against deflection.

While the invention has been described and illustrated in its several preferred embodiments, it should be understood that the invention is not to be limited to the precise details herein illustrated and described since the same may be carried out in other ways falling within the scope of the invention as claimed.

What is claimed:

1. A rigid metallic floor panel constructed to be supported in horizontal operative position at the edges or corners and sustain heavy floor loads without appreciable deflection, said panel comprising in combination, a pair of substantially flat metal sheets arranged in superimposed vertically spaced relationship, the upper of said sheets being rigid and imperforate to resist compression and the lower sheet having a checkerboard grid comprising -a set of parallel, straight strips extending longitudinally substantially from edge to edge of said sheet and a second similar set of parallel, straight strips extending transversely substantially from edge to edge of said sheet, said strips providing evenly arranged, parallel rows of openings therebetween, strut members integral with certain edges of said grid and extending upwardly therefrom into firm engagement with the lower surface of said upper sheet and fixed thereto to transmit load forces from said upper compression sheet to said lower tension sustaining sheet, the pe ripheral edges of said sheets being bent at right angles to form overlapping flanges extending toward each other, means for connecting said flanges to each other, the terminal edge of the flange on one sheet being bent slightly out of the plane of its flange to provide a continuous channel around the other sheet, a wear surface layer secured to the top of said other sheet and a finishing strip secured in said continuous channel and having its top surface flush with the top surface of said wear surface layer.

2. A rigid, metallic structural panel comprising a pair of spaced parallel sheets of similar shape and area, strut means extending from one sheet into engagement with the other sheet to transmit load forces from said one sheet to the other to render said panel rigid, the peripheral edges of said sheets being bent at right angles to form overlapping flanges extending toward each other, means for connecting said flanges to each other, the terminal edge of the flange on said one sheet being bent slightly out of the plane of said flange to provide a continuous channel around said other sheet, a wear surface layer secured to the top of said other sheet, and a finishing strip secured in said continuous channel and having its top surface flush with the top surface of said wear surface layer.

3. The floor panel according to claim 2 in which said finishing strip is formed with a channel extending upwardly thereinto and said channel receiving said terminal edge of said flange to connect said strip to said panel.

4. A rigid metallic floor panel constructed to be supported in horizontal operative position at the edges or corners thereof and sustain heavy floor loads without appreciable deflection, said panel comprising in combination, a pair of substantially flat metal sheets arranged in superimposed vertically spaced relationship, the upper of said sheets being rigid and imperforate to bear and distribute loads supported by said panel and the lower sheet having a checkerboard grid comprising a first set of parallel, straight strips extending longitudinally substantially from edge to edge of said sheet and a second similar set of parallel, straight strips extending transversely to said first set and substantially from edge to edge of said sheet, said strips providing evenly arranged, parallel rows of openings therebetween, strut members integral with certain edges of said grid strips and extending upwardly therefrom into firm engagement with the lower surface of said upper sheet and fixed thereto to transmit load forces from said upper sheet to said lower tension-sustaining sheet, the peripheral edges of said sheets being bent at right angles to form overlapping flanges extending toward each other, means for connecting said flanges to each other, a portion of the flanges of one of said sheets being bent from the planes of said flanges to space the same from opposed portions of the flanges of the other sheet, and thereby provide a continuous channel around the periphery of said panel, a wear surface layer secured to the top of said upper sheet, and a finishing strip supported in said continuous channel and having its top surface flush with the top surface of said wear surface layer.

5. A rigid metallic floor panel constructed to be supported in horizontal operative position at the edges or corners and sustain heavy floor loads without appreciable deflection, said panel comprising in combination, a pair of substantially flat metal sheets arranged in superimposed vertically spaced relationship, the upper of said sheets being rigid and imperforate to bear and distribute loads supported by said panel and the lower sheet having a checkerboard grid comprising a first setof parallel, straight strips extending longitudinally substantially from edge to edge 'of said sheet and -a second similar set of parallel, straight strips extending transversely to said first set substantially from edge to edge of said sheet, said strips providing evenly arranged, parallel rows of openings therebetween, strut members integral with certain edges of said grid strips and extending upwardly therefrom into firm engagement with the lower surfaceof said upper sheet and fixed thereto to transmit load forces fromsaid upper sheet to said lower tension-sustaining sheet, the peripheral edges of atleast one of said sheets being bent at right angles tothe plane of said sheet to form a marginal bracing flange around all edges of saidsheet and connected to the periphery of the other sheet, the terminal edge of said bracing flange being bent out of the plane of said flange and arranged in conjunction with the periphery of the other sheet to form a narrow longitudinal rib extending around all sides of said panel, a wear surface'layer secured to the top of said other sheet, and a channel-shaped finishing strip receiving said longitudinal rib within the channel thereof to secure said strip to said panel, saidfinishing strip closely surrounding the edges of said wear surface layer and having its top surface flush with said layer.

6. The floor panel according to claim in which said i one of said panels having itsperipheral edges bent at right angles to the plane thereof is the lower one having the checkerboard grid.

7. A rigid metallic floor panel constructed to be supported in horizontal operative position at the edges or corners and sustain heavy floor loads without appreciable deflection, said panel comprising in combination, a pair of substantially flat metal sheets of similar-shape and arranged in superimposed vertically spaced relationship, flange means on the edges of at least one sheet'bent toward the other'sheet and engagingthe edges thereof,

means connecting said edges "of said sheets together, the

uppermost of said sheets being rigid and imperforate to bear and distributea load 'when placed thereupon and the lower sheet'having'a planar'chefckerboard grid extending substantially to all edges of the sheet throughout the entire area thereof 'and'being substantially to said uppermost sheet to sustain tension, said grid comprising two 'sets of parallehstraight transversely spaced strips and'said sets respectively being arranged transversely to each other to provide parallel rows of substantially square throughout the length thereof and the outer ends of said strut members which'are of substantially similar width thereto being bent transversely to said strut members and abutting the undersurfaceof said upper sheet and fixed thereto to transmit load forces from said uppermost loadsustaining sheet to said lowertension-sustainingsheet, said bent outer ends of said 'strut bracing the same against buckling throughout the length thereof and said strut members on the edges of the openings being disposedat different opposed edges of the opening from those in an adjacent opening, thereby to provide ample access'to the space between said sheets to effect connection thereof while affordingsubstantial and uniformly spaced bracing areas for said uppermostsheet by the resulting arrangement of bent ends on said strut members as aforesaid.

8, The metallic floor panel according to claim7 further characterized by the struts of said lower'sheet being formed by said lower sheet initially having H-shaped incisions formed therein to provide a pair of rectangular tongues of similar lengths at opposite sides of each grid opening and each comprising one of said strut'members, the opposite'sidesedges' of said strut members being substantially parallel to each other and said bent outer ends of said strut members projecting from each grid opening extending toward 'each other and'being as wide as said strut members in a'direc'tion parallel to the bend connecting said ends to said strut members and having a length substantially at least half thelength of each strut, whereby said bent outer ends are'reinforced by the angular relationship of said strut members thereto and also thereby'aifo'rd substantial means abutting said uppermost sheet to resi'stbending thereof when subjected to concentrated loads'and also provide substantial areas within which to applywelding.

References Cited by'the Examiner UNITED STATES PATENTS 1,576,559 3/1926' Swift 52-621 3,008,551 11/1961 C016; 52615X 3,018,209 1/1962' Dijksterhuis 61111.1 52615 X 7 FOREIGN PATENTS 1,045,315 11/1953 France.

168,616 9/1921 Great Britain.

FRANK L ABBOTT, Primary Examiner.

RICHARD'W. COOKE, JR., Examiner,

L. R. RADANO'VIC, M. o. WARNECKE,

Assistant Examiners. 

2. A RIGID, METALLIC STRUCTURAL PANEL COMPRISING A PAIR OF SPACED PARALLEL SHEETS OF SIMILAR SHAPE AND AREA, A STRUT MEANS EXTENDING FROM ONE SHEET INTO ENGAGEMENT WITH THE OTHER SHEET TO TRANSMIT LOAD FORCES FROM SAID ONE SHEET TO THE OTHER TO RENDER SAID PANEL RIGID, THE PERIPHERAL EDGES OF SAID SHEETS BEING BENT AT RIGHT ANGLES TO FORM OVERLAPPING FLANGES EXTENDING TOWARD EACH OTHER, MEANS FOR CONNECTING SAID FLANGES TO EACH OTHER, THE TERMINAL EDGE OF THE FLANGE ON SAID ONE SHEET BEING BENT SLIGHTLY OUT OF THE PLANE OF SAID FLANGE TO PROVIDE A CONTINUOUS CHANNEL AROUND SAID OTHER SHEET, A WEAR SURFACE LAYER SECURED TO THE TOP OF SAID OTHER SHEET, AND A FINISHING STRIP SECURED IN SAID CONTINUOUS CHANNEL AND HAVING ITS TOP SURFACE FLUSH WITH THE TOP SURFACE OF SAID WEAR SURFACE LAYER. 